Digitized road maps have application to navigation systems for motor vehicles, among other things. The information concerning the road network is stored with the aid of segment starting points and segment end points on a data carrier, for instance, a CD-ROM.
A method for generating a road network map is known from German Patent No. 101 14 412, in which the pattern of the road is described by a clothoid between a segment starting point and a segment end point. The respective position of the vehicle or the pattern of the road segment is calculated.
An alternative method is also described in German Patent No 101 14 412, in which the pattern of the road between a segment starting point and a segment end point is described by a straight line. Depending on the curvature of the pattern of the road, the segment starting points and the segment end points are at different distances apart, since one condition says that the direct connection between a segment starting point and a segment end points must not leave the actual pattern of the road. That means that, in the case of curvy patterns of the road, the number of segment starting points and segment end points increases, and with that the quantity of data to be stored also increases.
The composition of respective linear partial pieces has the affect that, in the computation of the length of a stretch of path, a length error is generated. In addition, the accuracy and quality of the segment's starting points and end points and of the virtual road pattern are not sufficient for computing the curvature relationships of the route accurately in such a way that, for instance, a reliable function can be implemented for a curve warning system and/or additional vehicle assistance systems.